Dataset: GT10-11 - Tritium

Name: Tritium concentration from R/V Knorr cruises KN199-04 (GT10) and KN204-01 (GT11) in the Subtropical northern Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)
Published: 2016-03-10
Keywords: oceans

Cite This Dataset

Project:

U.S. GEOTRACES North Atlantic Transect (U.S. GEOTRACES NAT)

Program:

U.S. GEOTRACES (U.S. GEOTRACES)

Principal Investigator:

William J. Jenkins (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

10 March 2016

Version Date:

2016-03-10

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Data URL:

https://www.bco-dmo.org/dataset/3824/data

Tritium concentration from R/V Knorr cruises KN199-04 (GT10) and KN204-01 (GT11) in the Subtropical northern Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)

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Description

Status note: This dataset was revised on 10 March 2016. These data replace the previously submitted dataset, which contained erroneous values due to a software bug.

Concentration of Tritium from Niskin bottle samples from the KN199-04 (GT10) and KN204-01 (GT11) cruises. Station, cast, and Niskin bottle numbers are provided along with CTD pressure.

Please note that some US GEOTRACES data may not be final, pending intercalibration results and further analysis. If you are interested in following changes to US GEOTRACES NAT data, there is an RSS feed available via the BCO-DMO US GEOTRACES project page (scroll down and expand the "Datasets" section).

Acquisition Description

Sampling Description:
Tritium samples were transferred from Niskin bottles to cleaned 1 liter flint glass bottles (Lott and Jenkins, 1998).

Sample Processing:
Tritium water samples were transferred into specially prepared 1 liter aluminosilicate flasks and stored for at least 6 months for measurement of tritium by 3He regrowth.

Sample Analysis:
Tritium measurements were made by peak height manometry of an appropriately sized marine air standard (Lott and Jenkins, 1984) to an accuracy of better than 0.5% in quadrature with ion counting statistics limits. Uncertainties are therefore reported on a per-sample basis.

References:
Lott, D.E., Jenkins, W.J., 1984. An automated cryogenic charcoal trap system for helium isotope mass spectrometry. Review of Scientific Instruments 55, 1982-1988. doi: 10.1063/1.1137692
Lott, D.E., Jenkins, W.J., 1998. Advances in the analysis and shipboard processing of tritium and helium samples. International WOCE Newsletter 30, 27-30.

Processing Description

The data are flagged using the WOCE protocol.

Parameter names were modified to conform with BCO-DMO naming conventions.

lat_nom and lon_nom were added by BCO-DMO from station waypoints provided by the Chief Scientist of cruise KN199-04.

History:
Version 20 Dec 2012: Initial data submitted to BCO-DMO.
Version 04 Jan 2013: There was a calibration error in the first submission (an approximately 2% offset), which was corrected in the 04 Jan 2013 version.
Version 10 Jan 2013: An additional correction to a single quality flag was made on 10 Jan 2013.
Version 26 Nov 2013: GT11 data was added.
Version 10 March 2016: Replaced dataset with revised version. Includes addtional columns (temp, sal) and includes corrections to erroneous values in previous version that were due to a software bug.

Additional GEOTRACES Processing: After the data were submitted to the International Data Management Office, BODC, the office noticed that important identifying information was missing in many datasets. With the agreement of BODC and the US GEOTRACES lead PIs, BCO-DMO added standard US GEOTRACES information, such as the US GEOTRACES event number, to each submitted dataset lacking this information. To accomplish this, BCO-DMO compiled a 'master' dataset composed of the following parameters: station_GEOTRC, cast_GEOTRC (bottle and pump data only), event_GEOTRC, sample_GEOTRC, sample_bottle_GEOTRC (bottle data only), bottle_GEOTRC (bottle data only), depth_GEOTRC_CTD (bottle data only), depth_GEOTRC_CTD_rounded (bottle data only), BTL_ISO_DateTime_UTC (bottle data only), and GeoFish_id (GeoFish data only). This added information will facilitate subsequent analysis and inter comparison of the datasets.

Bottle parameters in the master file were taken from the GT-C_Bottle_GT10, GT-C_Bottle_GT11, ODF_Bottle_GT10, and ODF_Bottle_GT11 datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the Event_Log_GT10 and Event_Log_GT11 datasets. McLane pump cast numbers missing in event logs were taken from the Particulate Th-234 dataset submitted by Ken Buesseler.

A standardized BCO-DMO method (called “join”) was then used to merge the missing parameters to each US GEOTRACES dataset, most often by matching on sample_GEOTRC or on some unique combination of other parameters.

If the master parameters were included in the original data file and the values did not differ from the master file, the original data columns were retained and the name of the parameters were changed from the PI-submitted names to the standardized master names. If there were differences between the PI-supplied parameter values and those in the master file, both columns were retained. If the original data submission included all of the master parameters, no additional columns were added, but parameter names were modified to match the naming conventions of the master file.

See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-0926659

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
KN199-04	GT10 USGT-NAT-2010 KN199-4 GNAT U.S. GEOTRACES NAZT Leg 1 knorr199-4/5 Section Cruise (GA03) 316N20101015 GA03	2010-10-15	R/V Knorr	William J. Jenkins (Chief Scientist) Edward A. Boyle (Co-Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info
KN204-01	GT11 KN204-01A KN204-01B USGT-NAT-2011 USGNAZT GNAT 316N20111106 KN204-1 GA03	2011-11-06	R/V Knorr	Edward A. Boyle (Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info

Instruments

Mass Spectrometer

Supplied Description:

The mass spectrometer used for measurement was known as 'MS1'. This is a custom-built instrument located at the Isotope Geochemistry Facility (IGF) at Woods Hole Oceanographic Institution (WHOI). The MS1 is a 10-inch radius, 90-degree magnetic sector instrument dedicated to the measurement of tritium, helium, and neon in seawater and groundwater samples. For a full description, see http://www.whoi.edu/sbl/liteSite.do?litesiteid=28952&articleId=47708

Instrument Type

Generic Name: Mass Spectrometer

Acronym: Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.

Niskin bottle

Supplied Description:

Instrument Type

Generic Name: Niskin bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/

Generic Description:

A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
press	Pressure from CTD.	dbar	press
Tritium	Concentration of Tritium.	T.U. (tritium units)	radioactive_isotope_conc
Tritium_err	Tritium concentration error.	T.U. (tritium units)	radioactive_isotope_err
Tritium_flag	Tritium concentration quality flag using the WOCE protocol.	unitless	q_flag
lat_nom	Nominal latitude of station. Obtained from KN199-04 station waypoints provided by Chief Sci.	decimal degrees	lat_n
lon_nom	Nominal longitude of station. Obtained from KN199-04 station waypoints provided by Chief Sci.	decimal degrees	lon_n
cruise_id	Official cruise identifier e.g. KN199-04 = R/V Knorr cruise number 199-04.	dimensionless	cruise_id
station_GEOTRC	GEOTRACES station number; ranges from 1 through 12 for KN199-04 and 1 through 24 for KN204-01. Stations 7 and 9 were skipped on KN204-01. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'station'; this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	dimensionless	station
cast_GEOTRC	Cast identifier numbered consecutively within a station. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'cast'; this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	dimensionless	cast
event_GEOTRC	Unique identifying number for US GEOTRACES sampling events; ranges from 2001 to 2225 for KN199-04 events and from 3001 to 3282 for KN204-01 events. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	event
sample_GEOTRC	Unique identifying number for US GEOTRACES samples; ranges from 5033 to 6078 for KN199-04 and from 6112 to 8148 for KN204-01. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	sample
sample_bottle_GEOTRC	Unique identification numbers given to samples taken from bottles; rangies from 1 to 24; often used synonymously with bottle number. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'bottle'; this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	dimensionless	sample
bottle_GEOTRC	Alphanumeric characters identifying bottle type (e.g. NIS representing Niskin and GF representing GOFLO) and position on a CTD rosette. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	bottle
depth_GEOTRC_CTD	Observation/sample depth in meters; calculated from CTD pressure. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
BTL_ISO_DateTime_UTC	Date and time (UTC) variable recorded at the bottle sampling time in ISO compliant format. Values were added from the intermediate US GEOTRACES master file (see Processing Description). This standard is based on ISO 8601:2004(E) and takes on the following form: 2009-08-30T14:05:00[.xx]Z (UTC time)	YYYY-MM-DDTHH:MM:SS[.xx][+/-TZ]	ISO_DateTime_UTC
cruise_name	Cruise name.	dimensionless	cruise_name
temp	Water temperature, from CTD. (Originally called 'CTDTMP')	degrees Celsius	temp
sal	Salinity, from CTD. (Originally called 'CTDSAL')	practical salinity units (PSU)	sal

Database

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Dataset: GT10-11 - Tritium